P1411: FIRST EVALUATION OF A MOBILE HEALTH APP DEVELOPED TO MONITOR ACUTE TOXICITIES AFTER CAR T-CELL THERAPY: A THINK ALOUD STUDY WITH PATIENT EXPERTS
Authors: Milan Kos, Anne Mea Spanjaart, Liesbeth Van den Berg, Elise R.A. Pennings, Inger Nijhof, Linda Peute, Marie José Kersten, Martijn Van Oijen
Journal: HemaSphere (2023)

Topic: 25. Gene therapy, cellular immunotherapy and vaccination - Clinical Background: Prompt recognition of acute chimeric antigen receptor T (CAR T)-cell-mediated toxicity is crucial, because adequate and timely management can prevent or reverse potential life-threatening complications. A mobile health (mHealth) app was developed to support outpatient monitoring after CAR T-cell infusion and provide instructions on when to contact the hospital. It allows patients and informal caregivers to recognize, evaluate and report signs and symptoms marking potential acute toxicities using wearable measurements, symptom reporting, and caregiver-performed assessments. Aims: This study evaluates the usability and perceived usefulness of aforementioned app to determine whether mHealth development by physicians suits the end-users monitoring needs in the outpatient setting after CAR T-cell infusion. Methods: A total of 12 patient experts, who had undergone CAR T-cell treatment with axicabtagene ciloleucel or brexucabtagene autoleucel for Diffuse Large B-cell Lymphoma (DLBCL) and Mantle Cell lymphoma (MCL), respectively, were included. All participants were in complete metabolic response and participated in think aloud usability sessions in which they performed 9 tasks using the app on their own smartphone. Think aloud sessions were recorded, transcribed and analyzed. Usability problems were rated in accordance with the Nielsen severity scale. Moreover, participants were asked to rate the usability of the app by completing the eHealth UsaBility Benchmarking Instrument (HUBBI, 0-5 scale). Satisfaction was evaluated on a 0-10 scale and with the Net Promotor Score. Results: Median age of participants was 60 years (range 53-70) and 67% were male. Mean time after CAR T-cell infusion was 19.7 months (range 1.9-49.8). Used smartphone operating systems were iOS (50%) and Android (50%). Mean task completion rate was 84% (range 67%-100%). In total, 26 unique usability problems were identified, of which 10 had severity ³3. The main usability problems concerned the navigation through the app (mainly iOS) and unintuitive layout design. Furthermore, 83% of participants found and understood the instructions page in the app. HUBBI scores are depicted in Figure 1. iOS users gave lower usability scores in all categories. All participants rated the perceived usefulness of the app as very high and would have liked to use the app if it had been available after their CAR T-cell infusion. Satisfaction was rated high on HUBBI (4.33), Net Promotor Score (+83) and overall satisfaction (9.0). Summary/Conclusion: This think aloud usability study showed that the physician-developed mHealhth app was considered valuable by patient experts and could meet their needs. Perceived usefulness and satisfaction were rated high. Difficulties in navigating the app impacted the usability scores and will be addressed for redesign. The positive results of this usability study show promise in implementing this app for future CAR T-cell patients and enhancement of safe outpatient treatment monitoring.Figure 1. Results of HUBBI subcategories for all participants and subdivided between iOS and Android users. Keywords: CAR-T